Cellular characterisation of the GCKR P446L variant associated with type 2 diabetes risk

AIMS/HYPOTHESIS

Translation of genetic association signals into molecular mechanisms for diabetes has been slow. The glucokinase regulatory protein (GKRP; gene symbol GCKR) P446L variant, associated with inverse modulation of glucose- and lipid-related traits, has been shown to alter the kinetics of glucokinase (GCK) inhibition. As GCK inhibition is associated with nuclear sequestration, we aimed to determine whether this variant also alters the direct interaction between GKRP and GCK and their intracellular localisation.

METHODS

Fluorescently tagged rat and human wild-type (WT)- or P446L-GCKR and GCK were transiently transfected into HeLa cells and mouse primary hepatocytes. Whole-cell and nuclear fluorescence was quantified in individual cells exposed to low- or high-glucose conditions (5.5 or 25 mmol/l glucose, respectively). Interaction between GCK and GKRP was measured by sensitised emission-based fluorescence resonance energy transfer (FRET) efficiency.

RESULTS

P446L-GKRP had a decreased degree of nuclear localisation, ability to sequester GCK and direct interaction with GCK as measured by FRET compared with WT-GKRP. Decreased interaction was observed between WT-GKRP and GCK at high compared with low glucose, but not between P446L-GKRP and GCK. Rat WT-GKRP and P446L-GKRP behaved quite differently: both variants responded to high glucose by diminished sequestration of GCK but showed no effect of the P446L variant on nuclear localisation or GCK sequestration.

CONCLUSIONS/INTERPRETATION

Our study suggests the common human P446L-GKRP variant protein results in elevated hepatic glucose uptake and disposal by increasing active cytosolic GCK. This would increase hepatic lipid biosynthesis but decrease fasting plasma glucose concentrations and provides a potential mechanism for the protective effect of this allele on type 2 diabetes risk.

Tacticity and surface chemistry effects on the glass transition temperature of thin supported PMMA films

The glass transition temperature (Tg) of thin supported films of stereoregular poly(methyl methacrylate) on silicon has been investigated by ellipsometry in temperature. The Tg of the spin coated layers of isotactic PMMA increases for thickness lower than 100 nm whereas a depression of the Tg is observed for the syndiotactic PMMA. This opposite trend in the Tg variation in thin layer between the two isomers evidenced a fascinating effect of the chain organization at an interacting interface. Hydrofluric acid surface etching of the silicon wafer was shown to decrease the threshold thickness at which the change in Tg occurs for both PMMA isomers. The influence of the interfacial interactions along with the tacticity dependent characteristics of the polymer will be discussed.

Prioritizing policy interventions to improve diets? Will it work, can it happen, will it do harm?

Policies from non-health sectors have considerable impacts on the food environment and in turn on population nutrition. Health impact assessment (HIA) methods have been developed to identify the potential health effects of non-health policies; however, they are underused both within and outside the health sector. HIA and other assessment methods and tools can be used more extensively in health promotion to assist with the identification of the best policy options to pursue to improve and protect health. A participatory process is presented in this paper which combines HIAs with feasibility and effectiveness assessments. The intention is to enable health promoters to more accurately identify which policy change options would be most likely to improve diets, considering both impact and likelihood of implementation. The process was successfully used in Fiji and Tonga and provided a more systematic way of understanding which policy interventions showed the most promise.

Creating community action plans for obesity prevention using the ANGELO (Analysis Grid for Elements Linked to Obesity) Framework

Community-based interventions are an important component of obesity prevention efforts. The literature provides little guidance on priority-setting for obesity prevention in communities, especially for socially and culturally diverse populations. This paper reports on the process of developing prioritized, community-participatory action plans for obesity prevention projects in children and adolescents using the ANGELO (Analysis Grid for Elements Linked to Obesity) Framework. We combined stakeholder engagement processes, the ANGELO Framework (scans for environmental barriers, targeted behaviours, gaps in skills and knowledge) and workshops with key stakeholders to create action plans for six diverse obesity prevention projects in Australia (n = 3), New Zealand, Fiji and Tonga from 2002 to 2005. Some sites included sociocultural contextual analyses in the environmental scans. Target groups were under-5-year-olds (Australia), 4-12-year-olds (Australia) and 13-18-year-olds (all four countries). Over 120 potential behavioural, knowledge, skill and environmental elements were identified for prioritization leading into each 2-day workshop. Many elements were common across the diverse cultural communities; however, several unique sociocultural elements emerged in some cultural groups which informed their action plans. Youth were actively engaged in adolescent projects, allowing their needs to be incorporated into the action plans initiating the process of ownership. A common structure for the action plan promoted efficiencies in the process while allowing for community creativity and innovation. The ANGELO is a flexible and efficient way of achieving an agreed plan for obesity prevention with diverse communities. It is responsive to community needs, combines local and international knowledge and creates stakeholder ownership of the action plan.